Teleprinter subscriber station



NOV. 2, 1954 Q MOSER 2,693,502

TELEPRINTER SUBSCRIBER STATION Filed March 17, 1953 II, g, 7/ li 2 l 61 I 5. 5 EU =r M;

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United States Patent :My invention relates to printing :telegraphs "of the 'start stop :typein which a keyboard at the transmitting station "controls the emission of code ipul'se combinations through a single channel to the ireceiving station where the pulse combinations are appliedito a pulse responsive control tmagnet "that causes ta translating mechanism to type or print "a character correspondingto the particular pulsercombination being received at a time.

vin the "customary subscriber system of this kind, the coil :circuit of the control magnet in the :receiving subscriber station is connected between the two leads or poles of "the communication .line energized :from the exchange, and the control magnet is actuated directly by the current flowing :in the line. :Since ithe magnitude of "the line current .is small, the power requirements of thecontrol magnet'must be kept within ic'orrespondingly small limits. As a result,thezreceiver mechanism controlled "by the .magnet has a delicate, light-weight con- 'struction whose proper adjustment is critical and demands careful attention. I 7

:It is an object of my sinventio'n to :increase 'the permissible power capacity of the pulse-responsive freceiver control magnet'in such teleprinter subscriber lst-ations to thereby secure a less difficile .and .more reliable operation of the receiver mechanism, or to 'permit a generally more rugged design of the pulseetranslating re- 40 ceiver mechanism than heretofore applicable.

To achieve these objects, and in accordance with a featureof my invention, I connect the pulse responsive control magnet "in the teleprinter receiver station into a local excitation circuitand control this circuit by a 5 relay connected in the-receiver loop dot the transmission line. The .power for operating the "indirectly controlled pulse-responsive magnet is preferably supplied from the power line by a rectifier as usually available in subscriber stations for energizingthe electric equipment or for operating the drive motors'of the :teletypewriter or printer to be controlled by the magnet.

According to another feature of my invention, Iproride the magnet-controllingrelay with"two coactive relay windings 0f whichone'is excited by the code-combinatien pulses while the other is connected to the "local power supply to provide the relay with preexcitation to secure a rapid response to the occurrence of current pauses in the pulse-excited winding.

According to still another feature of the invention, the teleprinter control magnet is equipped with two magnet systems or units acting in a mutually opposed sense upon the same armature, which are alternately energized by the above-mentioned relay to magnetically move the armature in one or the other direction, thus securing an extremely fast response of the magnet by eliminating the necessity for armature biasing springs whose force must be overpowered when the armature is magnetically attracted.

These and more specific features of my invention will be apparent from the embodiments exemplified by the drawing, in which- Fig. 1 shows schematically a teletypewriter station witlh a control magnet with a spring-biased armature, an

Fig. 2 is a similar illustration of a similar subscriber station with a modified control magnet not requiring a biasing spring.

The same reference characters are used in both figures for denoting respectively similar elements.

According to Fig. 1, the mechanism R of the illus- Geo tra'ted subscriber station ::a control magnets-assembly, denoted as a whole by EM, whose armature oscillates in the rhythm of the code :pulse trains arriving :from the transmitting "subscriber station ;to thereby control the selection and printing iof a corresponding rtype character. The magnet assembly comprises a rigid frame 1 of non-magnetic nmaterial firmly secured to a :stationary support or housing structure fi2 'of the receiver mechanism. -A three-legged magnetiza'ble core Suis rigidly mounted on frame 1 and carries an excitation :coil 4 on its center leg. The qpole Yfaces -'of*the three ;legs lie in a common plane. The sarmature'fiof -xthexrnagnet is disposed in .front of the pole afaces :in the magnetic field produced by the :excitationzofccoil l. Armature :5 is pivotally movable-about ajpivot forrned-by two coaxial .pins of which only the upper spin :6 .is visible in the illustration. The pivot pins .are revolvable :in respective bores of frarne .1. Armature '5 is normally pulled away from core '3 by a "biasing spring 7 which has one end attached to the armature while the other end is secured'toran adjusting :screw8. An arm :9 of armature Sis linked to an axially .movable rod 10 which transmits the armature rmovements zto the-type-selecti'ng control mechanism proper (not :illustrated). Various designs of such mechanisms in start-stop teletypewriters and similar teleprinters .for single-channel operation .by code pulses, especially of a five-unit code, are known and suitable for .use'with the invention, the particular design of the mechanism, including the: pulse-responsive control :magnet, being not essential :to the .invention. The particular design=of thezmagneta assembly there chosen for illustration .is in accordance with the onelpertaining to the-teletypewriter control mechanism disclosed in my copending application, Serial :No. 388,986, filed October 29, 1953, to which re'ferencemayrbmhad if :desired.

The coil 4-of the receiver :control magnet 'EMis :connected into alocal excitation circuit whose current. source consists of a rectifier- GL. The rectifier :is connected through a transformer Tlto a utilityipowerline and may also serve to supply current 'to theimotors or otherelectrically operated parts i of rthe 'telety-ping apparatus. :A resistor W2 for adjusting the local excitation :current and a control contact ir are series connected with each other in the local excitation circuit .11=iof magnet.-coil4.

The control contact ir formsthe contact :member of a polarized pulse-receiving relay :JR "whose polarized magnetcore is equipped with twoi relay windings F12 .and 13. Winding 12 is connected across the two line terminals a and b of the'subscribert'station infloop connection with the transmitting zpulsecontact :sk of the station. Hense, when :the station is operating as a :receiver, the code pulses, arriving through :the transmission channel from the exchange, pass serially .throughwindinglZ and the then-closed transmitter "contact sk. vWhentheJstation is operating as a transmitter, the contact sk'iis opened and closed. in accordance with the-code;fcombinationsito correspondingly interrupt and restore :theline current thus transmitting the proper code pulses as current pauses to the exchange. The winding 13 of relay IR is connected to the rectifier GL in series with an adjustable resistor W1 to provide the relay with pre-excitation whose magnitude can be adjusted at resistor W1. Due to this pre-excitation, the relay contact ir is kept in the illustrated circuitclosing position thus energizing the coil 4 of magnet EM from rectifier GL as long as the subscriber station is actively connected to the line from the exchange so that line current is flowing through coil 12.

The pulses (current pauses) being received, or being issued by the transmitter contact sk, disturb the balance condition of relay JR so that it temporarily opens its control contact ir to interrupt the excitation of control magnet EM in the rhythm of the pulses.

It has been found that in apparatus according to Fig. 1, the dependency of the required magnet attraction of the armature upon the mechanical biasing force of the return spring in the control magnet EM tends to have a very unfavorable effect upon the flip-over period of the armature due, especially, to the square-law dependency of the spring force upon the spring deflection.

The embodiment shown in Fig. 2 avoids this deficiency by having the return movement of the armature also controlled by magnetic force. To this end, the receiver control magnet EM is equipped with two magnet units denoted summarily by EM1 and EM2 respectively, each magnet unit having a core and a coil similar to elements 3 and 4 of Fig. 1. As illustrated in Fig. 2, the unit EM2 serves as the active control magnet while the unit EM1 operates an a return-bias magnet.

The coils of both magnet units EM1 and EM2 are parallel connected in the local excitation circuit 11 energized from rectifier GL under control by the contact member ir of the polarized pulse-receiving relay JR. Contact member ir coacts with a normally closed contact 15 series connected with magnet unit EM2 through an adjusting resistor W3, and with a normally open contact 16 series connected with magnet unit EM1 through an adjusting resistor W4. The resistors W3 and W4 permit adjusting the excitation current for each unit independent of the other. The armature is disposed between the respective pole faces of the two units EM1 and EM2 to change its position depending upon which of the units is energized at a time.

The polarized relay JR has two differential windings 12 and 13. Winding 12 serves as the control winding and is connected across the line terminal a and b through the pulse transmitter contact sk. Winding 13 provides the relay with pre-excitation and is connected across the output terminals of the rectifier GL.

As in the embodiment of Fig. 1, any code pulses, transmitted to the exchange by operation of contact sk or received from the exchange, disturb the balance of relay JR so that contact member ir opens the circuit of magnet unit EM2 at contact 15 and temporarily closes the circuit of unit EM1 at contact 16. The resulting alternating build-up and decay of the magnet field causes the armature 5 to oscillate in accordance with the pulse combinations. That is, when the transmitter contact sk in the receiving or transmitting station is closed, the magnet unit EM1 is excited from the local power source and attracts the armature; and when contact sk is open, the unit EM2 is deenergized and the magnet unit EM1 is energized thus returning the armature to the position of rest.

The apparatus according to Fig. 2, therefore, receives the advantage that the attraction movement of the magnet armature is independent of the return bias, this being due to the elimination of return springs or other biasing means whose force must be overpowered by the magnetic attraction.

It will be obvious to those skilled in the art that various modifications other than those specifically described may be made without departing from the essence of my invention and within the scope of the claims annexed hereto.

I claim:

1. A teleprinter subscriber station, comprising a teleprinter mechanism having a reciprocable control member and having a control magnet, said magnet having two mutually. opposed magnet units forming a field space between each other and having a reciprocable armature disposed in said space to be magnetically moved between two positions depending upon which of said units is energized, said armature being connected with said control member for actuating said member, a local power source for energizing said two magnet units, a pulseresponsive relay having a make contact and a break contact series connected between said respective magnet units and said source for alternately energizing said units in response to code pulse combinations, said relay having a control winding, and a pulse-receiving circuit adapted for connection to a teleprinter communication line and connected with said winding.

2. A teleprinter subscriber station, comprising a telei printer mechanism having a pulse-responsive control magnet, a local power supply connected with said magnet to provide excitation therefor, a pulse-responsive relay having a movable armature, switch contact means actuated by said armature and connected between said power supply and said magnet for controlling said excitation, said relay having two coactive difierential relay windings, one of said windings being connected with said local power supply for pre-exciting said relay to provide a magnetic flux therein sufficient to hold said armature in opencircuit position of said contact means, a circuit having terminals for connection to a communication line and including a normallyclosed pulse transmitter contact as well as said other relay winding, said two relay windings when both excited providing in said relay a resultant differential flux sufiicient for attracting said armature to close-circuit position of said contact means to excite said magnet, whereby said magnet is controlled in response to current-interrupting pulse combinations in said circuit.

3. A teleprinter subscriber station, comprising a teleprinter mechanism having a reciprocable control member and having a control magnet, said magnet having two mutually opposed magnet units forming a field space between each other and having a reciprocable armature disposed in said space to be magnetically moved between two positions depending upon which of said units is energized, said armature being connected with said control member for actuating said member, a local power source for energizing said two magnet units, a pulseresponsive relay having a make contact and a break contact series connected between said respective magnet units and said source for alternately energizing said units in response to code pulse combinations, said relay having two coactive relay windings, one of said windings being connected with said local power source, a circuit having terminals for connection to a communication line and including a normally closed pulse transmitter contact as well as said other relay winding, said two relay windings when both excited having in said relay a resultant flux sufiicient for closing said breakcontact, whereby said break contact is opened and said make contact temporarily closed in response to current pauses occurring in said circuit.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 486,889 Neal et a1 Nov. 29, 1892 795,577 Cardwell July 25, 1905 2,340,065 Lang Jan. 25, 1944 

